Question

Could you please tell me how to pass a JSON String which looks like this:

{"lessons":[{"id":"38","fach":"D","stunde":"t1s1","user_id":"1965","timestamp":"0000-00-00 00:00:00"},{"id":"39","fach":"M","stunde":"t1s2","user_id":"1965","timestamp":"0000-00-00 00:00:00"}]}

I tried it like this:

SBJSON *parser =[[SBJSON alloc] init];
    NSArray *list = [[parser objectWithString:JsonData error:nil] copy];
    [parser release];
    for (NSDictionary *stunden in list)
    {
        NSString *content = [[stunden objectForKey:@"lessons"] objectForKey:@"stunde"];

    }

thanks in advance

best regards

Answer 1

Note that your JSON data has the following structure:

1. the top level value is an object (a dictionary) that has a single attribute called ‘lessons’
2. the ‘lessons’ attribute is an array
3. each element in the ‘lessons’ array is an object (a dictionary containing a lesson) with several attributes, including ‘stunde’

The corresponding code is:

SBJSON *parser = [[[SBJSON alloc] init] autorelease];
// 1. get the top level value as a dictionary
NSDictionary *jsonObject = [parser objectWithString:JsonData error:NULL];
// 2. get the lessons object as an array
NSArray *list = [jsonObject objectForKey:@"lessons"];
// 3. iterate the array; each element is a dictionary...
for (NSDictionary *lesson in list)
{
    // 3 ...that contains a string for the key "stunde"
    NSString *content = [lesson objectForKey:@"stunde"];

}

A couple of observations:

• In -objectWithString:error:, the error parameter is a pointer to a pointer. It’s more common to use NULL instead of nil in that case. It’s also a good idea not to pass NULL and use an NSError object to inspect the error in case the method returns nil

• If jsonObject is used only in that particular method, you probably don’t need to copy it. The code above doesn’t.